ClickHouse/dbms/src/Functions/GatherUtils/Algorithms.h

#pragma once

#include <Common/FieldVisitors.h>

#include <Functions/GatherUtils/Sources.h>
#include <Functions/GatherUtils/Sinks.h>

#include <ext/range.h>

namespace DB::ErrorCodes
{
    extern const int LOGICAL_ERROR;
}

namespace  DB::GatherUtils
{

/// Methods to copy Slice to Sink, overloaded for various combinations of types.

template <typename T>
void writeSlice(const NumericArraySlice<T> & slice, NumericArraySink<T> & sink)
{
    sink.elements.resize(sink.current_offset + slice.size);
    memcpySmallAllowReadWriteOverflow15(&sink.elements[sink.current_offset], slice.data, slice.size * sizeof(T));
    sink.current_offset += slice.size;
}

template <typename T, typename U>
void writeSlice(const NumericArraySlice<T> & slice, NumericArraySink<U> & sink)
{
    sink.elements.resize(sink.current_offset + slice.size);
    for (size_t i = 0; i < slice.size; ++i)
    {
        sink.elements[sink.current_offset] = slice.data[i];
        ++sink.current_offset;
    }
}

inline ALWAYS_INLINE void writeSlice(const StringSource::Slice & slice, StringSink & sink)
{
    sink.elements.resize(sink.current_offset + slice.size);
    memcpySmallAllowReadWriteOverflow15(&sink.elements[sink.current_offset], slice.data, slice.size);
    sink.current_offset += slice.size;
}

inline ALWAYS_INLINE void writeSlice(const StringSource::Slice & slice, FixedStringSink & sink)
{
    memcpySmallAllowReadWriteOverflow15(&sink.elements[sink.current_offset], slice.data, slice.size);
}

/// Assuming same types of underlying columns for slice and sink if (ArraySlice, ArraySink) is (GenericArraySlice, GenericArraySink).
inline ALWAYS_INLINE void writeSlice(const GenericArraySlice & slice, GenericArraySink & sink)
{
    if (typeid(slice.elements) == typeid(static_cast<const IColumn *>(&sink.elements)))
    {
        sink.elements.insertRangeFrom(*slice.elements, slice.begin, slice.size);
        sink.current_offset += slice.size;
    }
    else
        throw Exception("Function writeSlice expect same column types for GenericArraySlice and GenericArraySink.",
                        ErrorCodes::LOGICAL_ERROR);
}

template <typename T>
inline ALWAYS_INLINE void writeSlice(const GenericArraySlice & slice, NumericArraySink<T> & sink)
{
    sink.elements.resize(sink.current_offset + slice.size);
    for (size_t i = 0; i < slice.size; ++i)
    {
        Field field;
        slice.elements->get(slice.begin + i, field);
        sink.elements.push_back(applyVisitor(FieldVisitorConvertToNumber<T>(), field));
    }
    sink.current_offset += slice.size;
}

template <typename T>
inline ALWAYS_INLINE void writeSlice(const NumericArraySlice<T> & slice, GenericArraySink & sink)
{
    for (size_t i = 0; i < slice.size; ++i)
    {
        Field field = T(slice.data[i]);
        sink.elements.insert(field);
    }
    sink.current_offset += slice.size;
}

template <typename Slice, typename ArraySink>
inline ALWAYS_INLINE void writeSlice(const NullableSlice<Slice> & slice, NullableArraySink<ArraySink> & sink)
{
    sink.null_map.resize(sink.current_offset + slice.size);

    if (slice.size == 1) /// Always true for ValueSlice.
        sink.null_map[sink.current_offset] = *slice.null_map;
    else
        memcpySmallAllowReadWriteOverflow15(&sink.null_map[sink.current_offset], slice.null_map, slice.size * sizeof(UInt8));

    writeSlice(static_cast<const Slice &>(slice), static_cast<ArraySink &>(sink));
}

template <typename Slice, typename ArraySink>
inline ALWAYS_INLINE void writeSlice(const Slice & slice, NullableArraySink<ArraySink> & sink)
{
    sink.null_map.resize(sink.current_offset + slice.size);

    if (slice.size == 1) /// Always true for ValueSlice.
        sink.null_map[sink.current_offset] = 0;
    else if (slice.size)
        memset(&sink.null_map[sink.current_offset], 0, slice.size * sizeof(UInt8));

    writeSlice(slice, static_cast<ArraySink &>(sink));
}


template <typename T, typename U>
void writeSlice(const NumericValueSlice<T> & slice, NumericArraySink<U> & sink)
{
    sink.elements.resize(sink.current_offset + 1);
    sink.elements[sink.current_offset] = slice.value;
    ++sink.current_offset;
}

/// Assuming same types of underlying columns for slice and sink if (ArraySlice, ArraySink) is (GenericValueSlice, GenericArraySink).
inline ALWAYS_INLINE void writeSlice(const GenericValueSlice & slice, GenericArraySink & sink)
{
    if (typeid(slice.elements) == typeid(static_cast<const IColumn *>(&sink.elements)))
    {
        sink.elements.insertFrom(*slice.elements, slice.position);
        ++sink.current_offset;
    }
    else
        throw Exception("Function writeSlice expect same column types for GenericValueSlice and GenericArraySink.",
                        ErrorCodes::LOGICAL_ERROR);
}

template <typename T>
inline ALWAYS_INLINE void writeSlice(const GenericValueSlice & slice, NumericArraySink<T> & sink)
{
    sink.elements.resize(sink.current_offset + 1);

    Field field;
    slice.elements->get(slice.position, field);
    sink.elements.push_back(applyVisitor(FieldVisitorConvertToNumber<T>(), field));
    ++sink.current_offset;
}

template <typename T>
inline ALWAYS_INLINE void writeSlice(const NumericValueSlice<T> & slice, GenericArraySink & sink)
{
    Field field = T(slice.value);
    sink.elements.insert(field);
    ++sink.current_offset;
}



template <typename SourceA, typename SourceB, typename Sink>
void NO_INLINE concat(SourceA && src_a, SourceB && src_b, Sink && sink)
{
    sink.reserve(src_a.getSizeForReserve() + src_b.getSizeForReserve());

    while (!src_a.isEnd())
    {
        writeSlice(src_a.getWhole(), sink);
        writeSlice(src_b.getWhole(), sink);

        sink.next();
        src_a.next();
        src_b.next();
    }
}

template <typename Source, typename Sink>
void concat(const std::vector<std::unique_ptr<IArraySource>> & array_sources, Sink && sink)
{
    size_t sources_num = array_sources.size();
    std::vector<char> is_const(sources_num);

    auto checkAndGetSizeToReserve = [] (auto source, IArraySource * array_source)
    {
        if (source == nullptr)
            throw Exception("Concat function expected " + demangle(typeid(Source).name()) + " or "
                            + demangle(typeid(ConstSource<Source>).name()) + " but got "
                            + demangle(typeid(*array_source).name()), ErrorCodes::LOGICAL_ERROR);
        return source->getSizeForReserve();
    };

    size_t size_to_reserve = 0;
    for (auto i : ext::range(0, sources_num))
    {
        auto & source = array_sources[i];
        is_const[i] = source->isConst();
        if (is_const[i])
            size_to_reserve += checkAndGetSizeToReserve(typeid_cast<ConstSource<Source> *>(source.get()), source.get());
        else
            size_to_reserve += checkAndGetSizeToReserve(typeid_cast<Source *>(source.get()), source.get());
    }

    sink.reserve(size_to_reserve);

    auto writeNext = [& sink] (auto source)
    {
        writeSlice(source->getWhole(), sink);
        source->next();
    };

    while (!sink.isEnd())
    {
        for (auto i : ext::range(0, sources_num))
        {
            auto & source = array_sources[i];
            if (is_const[i])
                writeNext(static_cast<ConstSource<Source> *>(source.get()));
            else
                writeNext(static_cast<Source *>(source.get()));
        }
        sink.next();
    }
}

template <typename Sink>
void NO_INLINE concat(StringSources & sources, Sink && sink)
{
    while (!sink.isEnd())
    {
        for (auto & source : sources)
        {
            writeSlice(source->getWhole(), sink);
            source->next();
        }
        sink.next();
    }
}


template <typename Source, typename Sink>
void NO_INLINE sliceFromLeftConstantOffsetUnbounded(Source && src, Sink && sink, size_t offset)
{
    while (!src.isEnd())
    {
        writeSlice(src.getSliceFromLeft(offset), sink);
        sink.next();
        src.next();
    }
}

template <typename Source, typename Sink>
void NO_INLINE sliceFromLeftConstantOffsetBounded(Source && src, Sink && sink, size_t offset, ssize_t length)
{
    while (!src.isEnd())
    {
        ssize_t size = length;
        if (size < 0)
            size += static_cast<ssize_t>(src.getElementSize()) - offset;

        if (size > 0)
            writeSlice(src.getSliceFromLeft(offset, size), sink);

        sink.next();
        src.next();
    }
}

template <typename Source, typename Sink>
void NO_INLINE sliceFromRightConstantOffsetUnbounded(Source && src, Sink && sink, size_t offset)
{
    while (!src.isEnd())
    {
        writeSlice(src.getSliceFromRight(offset), sink);
        sink.next();
        src.next();
    }
}

template <typename Source, typename Sink>
void NO_INLINE sliceFromRightConstantOffsetBounded(Source && src, Sink && sink, size_t offset, ssize_t length)
{
    while (!src.isEnd())
    {
        ssize_t size = length;
        if (size < 0)
            size += static_cast<ssize_t>(src.getElementSize()) - offset;

        if (size > 0)
            writeSlice(src.getSliceFromRight(offset, size), sink);

        sink.next();
        src.next();
    }
}

template <typename Source, typename Sink>
void NO_INLINE sliceDynamicOffsetUnbounded(Source && src, Sink && sink, const IColumn & offset_column)
{
    const bool is_null = offset_column.onlyNull();
    const auto * nullable = typeid_cast<const ColumnNullable *>(&offset_column);
    const ColumnUInt8::Container * null_map = nullable ? &nullable->getNullMapColumn().getData() : nullptr;
    const IColumn * nested_column = nullable ? &nullable->getNestedColumn() : &offset_column;

    while (!src.isEnd())
    {
        auto row_num = src.rowNum();
        bool has_offset = !is_null && !(null_map && (*null_map)[row_num]);
        Int64 offset = has_offset ? nested_column->getInt(row_num) : 1;

        if (offset != 0)
        {
            typename std::decay_t<Source>::Slice slice;

            if (offset > 0)
                slice = src.getSliceFromLeft(offset - 1);
            else
                slice = src.getSliceFromRight(-offset);

            writeSlice(slice, sink);
        }

        sink.next();
        src.next();
    }
}

template <typename Source, typename Sink>
void NO_INLINE sliceDynamicOffsetBounded(Source && src, Sink && sink, const IColumn & offset_column, const IColumn & length_column)
{
    const bool is_offset_null = offset_column.onlyNull();
    const auto * offset_nullable = typeid_cast<const ColumnNullable *>(&offset_column);
    const ColumnUInt8::Container * offset_null_map = offset_nullable ? &offset_nullable->getNullMapColumn().getData() : nullptr;
    const IColumn * offset_nested_column = offset_nullable ? &offset_nullable->getNestedColumn() : &offset_column;

    const bool is_length_null = length_column.onlyNull();
    const auto * length_nullable = typeid_cast<const ColumnNullable *>(&length_column);
    const ColumnUInt8::Container * length_null_map = length_nullable ? &length_nullable->getNullMapColumn().getData() : nullptr;
    const IColumn * length_nested_column = length_nullable ? &length_nullable->getNestedColumn() : &length_column;

    while (!src.isEnd())
    {
        size_t row_num = src.rowNum();
        bool has_offset = !is_offset_null && !(offset_null_map && (*offset_null_map)[row_num]);
        bool has_length = !is_length_null && !(length_null_map && (*length_null_map)[row_num]);
        Int64 offset = has_offset ? offset_nested_column->getInt(row_num) : 1;
        Int64 size = has_length ? length_nested_column->getInt(row_num) : static_cast<Int64>(src.getElementSize());

        if (size < 0)
            size += offset > 0 ? static_cast<Int64>(src.getElementSize()) - (offset - 1) : -offset;

        if (offset != 0 && size > 0)
        {
            typename std::decay_t<Source>::Slice slice;

            if (offset > 0)
                slice = src.getSliceFromLeft(offset - 1, size);
            else
                slice = src.getSliceFromRight(-offset, size);

            writeSlice(slice, sink);
        }

        sink.next();
        src.next();
    }
}


template <typename SourceA, typename SourceB, typename Sink>
void NO_INLINE conditional(SourceA && src_a, SourceB && src_b, Sink && sink, const PaddedPODArray<UInt8> & condition)
{
    sink.reserve(std::max(src_a.getSizeForReserve(), src_b.getSizeForReserve()));

    const UInt8 * cond_pos = condition.data();
    const UInt8 * cond_end = cond_pos + condition.size();

    while (cond_pos < cond_end)
    {
        if (*cond_pos)
            writeSlice(src_a.getWhole(), sink);
        else
            writeSlice(src_b.getWhole(), sink);

        ++cond_pos;
        src_a.next();
        src_b.next();
        sink.next();
    }
}


/// Methods to check if first array has elements from second array, overloaded for various combinations of types.

template <bool all, typename FirstSliceType, typename SecondSliceType,
          bool (*isEqual)(const FirstSliceType &, const SecondSliceType &, size_t, size_t)>
bool sliceHasImpl(const FirstSliceType & first, const SecondSliceType & second,
                  const UInt8 * first_null_map, const UInt8 * second_null_map)
{
    const bool has_first_null_map = first_null_map != nullptr;
    const bool has_second_null_map = second_null_map != nullptr;

    for (size_t i = 0; i < second.size; ++i)
    {
        bool has = false;
        for (size_t j = 0; j < first.size && !has; ++j)
        {
            const bool is_first_null = has_first_null_map && first_null_map[j];
            const bool is_second_null = has_second_null_map && second_null_map[i];

            if (is_first_null && is_second_null)
                has = true;

            if (!is_first_null && !is_second_null && isEqual(first, second, j, i))
                has = true;
        }

        if (has && !all)
            return true;

        if (!has && all)
            return false;

    }

    return all;
}

#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wsign-compare"

template <typename T, typename U>
bool sliceEqualElements(const NumericArraySlice<T> & first, const NumericArraySlice<U> & second, size_t first_ind, size_t second_ind)
{
    return first.data[first_ind] == second.data[second_ind];
}

#pragma GCC diagnostic pop

template <typename T>
bool sliceEqualElements(const NumericArraySlice<T> &, const GenericArraySlice &, size_t, size_t)
{
    return false;
}

template <typename U>
bool sliceEqualElements(const GenericArraySlice &, const NumericArraySlice<U> &, size_t, size_t)
{
    return false;
}

inline ALWAYS_INLINE bool sliceEqualElements(const GenericArraySlice & first, const GenericArraySlice & second, size_t first_ind, size_t second_ind)
{
    return first.elements->compareAt(first_ind + first.begin, second_ind + second.begin, *second.elements, -1) == 0;
}

template <bool all, typename T, typename U>
bool sliceHas(const NumericArraySlice<T> & first, const NumericArraySlice<U> & second)
{
    auto impl = sliceHasImpl<all, NumericArraySlice<T>, NumericArraySlice<U>, sliceEqualElements<T, U>>;
    return impl(first, second, nullptr, nullptr);
}

template <bool all>
bool sliceHas(const GenericArraySlice & first, const GenericArraySlice & second)
{
    /// Generic arrays should have the same type in order to use column.compareAt(...)
    if (typeid(*first.elements) != typeid(*second.elements))
        return false;

    auto impl = sliceHasImpl<all, GenericArraySlice, GenericArraySlice, sliceEqualElements>;
    return impl(first, second, nullptr, nullptr);
}

template <bool all, typename U>
bool sliceHas(const GenericArraySlice & /*first*/, const NumericArraySlice<U> & /*second*/)
{
    return false;
}

template <bool all, typename T>
bool sliceHas(const NumericArraySlice<T> & /*first*/, const GenericArraySlice & /*second*/)
{
    return false;
}

template <bool all, typename FirstArraySlice, typename SecondArraySlice>
bool sliceHas(const FirstArraySlice & first, NullableSlice<SecondArraySlice> & second)
{
    auto impl = sliceHasImpl<all, FirstArraySlice, SecondArraySlice, sliceEqualElements<FirstArraySlice, SecondArraySlice>>;
    return impl(first, second, nullptr, second.null_map);
}

template <bool all, typename FirstArraySlice, typename SecondArraySlice>
bool sliceHas(const NullableSlice<FirstArraySlice> & first, SecondArraySlice & second)
{
    auto impl = sliceHasImpl<all, FirstArraySlice, SecondArraySlice, sliceEqualElements<FirstArraySlice, SecondArraySlice>>;
    return impl(first, second, first.null_map, nullptr);
}

template <bool all, typename FirstArraySlice, typename SecondArraySlice>
bool sliceHas(const NullableSlice<FirstArraySlice> & first, NullableSlice<SecondArraySlice> & second)
{
    auto impl = sliceHasImpl<all, FirstArraySlice, SecondArraySlice, sliceEqualElements<FirstArraySlice, SecondArraySlice>>;
    return impl(first, second, first.null_map, second.null_map);
}

template <bool all, typename FirstSource, typename SecondSource>
void NO_INLINE arrayAllAny(FirstSource && first, SecondSource && second, ColumnUInt8 & result)
{
    auto size = result.size();
    auto & data = result.getData();
    for (auto row : ext::range(0, size))
    {
        data[row] = static_cast<UInt8>(sliceHas<all>(first.getWhole(), second.getWhole()) ? 1 : 0);
        first.next();
        second.next();
    }
}

template <typename ArraySource, typename ValueSource, typename Sink>
void resizeDynamicSize(ArraySource && array_source, ValueSource && value_source, Sink && sink, const IColumn & size_column)
{
    const auto * size_nullable = typeid_cast<const ColumnNullable *>(&size_column);
    const NullMap * size_null_map = size_nullable ? &size_nullable->getNullMapData() : nullptr;
    const IColumn * size_nested_column = size_nullable ? &size_nullable->getNestedColumn() : &size_column;

    while (!sink.isEnd())
    {
        size_t row_num = array_source.rowNum();
        bool has_size = !size_null_map || (size_null_map && (*size_null_map)[row_num]);

        if (has_size)
        {
            auto size = size_nested_column->getInt(row_num);
            auto array_size = array_source.getElementSize();

            if (size >= 0)
            {
                auto length = static_cast<size_t>(size);
                if (array_size <= length)
                {
                    writeSlice(array_source.getWhole(), sink);
                    for (size_t i = array_size; i < length; ++i)
                        writeSlice(value_source.getWhole(), sink);
                }
                else
                    writeSlice(array_source.getSliceFromLeft(0, length), sink);
            }
            else
            {
                auto length = static_cast<size_t>(-size);
                if (array_size <= length)
                {
                    for (size_t i = array_size; i < length; ++i)
                        writeSlice(value_source.getWhole(), sink);
                    writeSlice(array_source.getWhole(), sink);
                }
                else
                    writeSlice(array_source.getSliceFromRight(length, length), sink);
            }
        }
        else
            writeSlice(array_source.getWhole(), sink);

        value_source.next();
        array_source.next();
        sink.next();
    }
}

template <typename ArraySource, typename ValueSource, typename Sink>
void resizeConstantSize(ArraySource && array_source, ValueSource && value_source, Sink && sink, const ssize_t size)
{
    while (!sink.isEnd())
    {
        auto array_size = array_source.getElementSize();

        if (size >= 0)
        {
            auto length = static_cast<size_t>(size);
            if (array_size <= length)
            {
                writeSlice(array_source.getWhole(), sink);
                for (size_t i = array_size; i < length; ++i)
                    writeSlice(value_source.getWhole(), sink);
            }
            else
                writeSlice(array_source.getSliceFromLeft(0, length), sink);
        }
        else
        {
            auto length = static_cast<size_t>(-size);
            if (array_size <= length)
            {
                for (size_t i = array_size; i < length; ++i)
                    writeSlice(value_source.getWhole(), sink);
                writeSlice(array_source.getWhole(), sink);
            }
            else
                writeSlice(array_source.getSliceFromRight(length, length), sink);
        }

        value_source.next();
        array_source.next();
        sink.next();
    }
}

}